DisplayLink and EVGA today announced that they have teamed to deliver a new generation of affordable USB graphics adapters (UGAs) for mass-market retail consumers. EVGA’s new UV Plus+ Family of products which consists of the UV12 and UV16 USB graphics adapters, are based on DisplayLink network display technology, enabling any available USB port on your desktop PC or notebook to be turned into an additional video output for use with another display. The GPU-less design utilizes a virtual driver and high-performance DDR memory with full support for Windows Vista Aero and high resolution capabilities. Once the USB 2.0 capable EVGA UGA is used to connect your system to an additional monitor, the following three video modes will be accessible: mirrored desktop, extended desktop and primary display. Furthermore the included software will let you expand (left, right, above or below), rotate (left, right, or upside-down), or mirror your virtual workspace. Both adapters are now available through EVGA’s network of partners with a sub-$100 price tag. Please proceed here for more information.

NCIX sells a little cheap USB-vga adapter, about 90 bucks. Its small, USB powered, and works good. The problem with usb is the bandwidth just isnt enough, those little things only do small resolutions, and won't do any 3D.

They are good for basic needs, I was using them to get multi-monitors out of a car-PC, because the pc didn't fit PCI cards.